Landing selector apparatus

ABSTRACT

Landing selector apparatus for use in an elevator control system. An output voltage whose magnitude signifies the location of the car in the hoistway is added to a voltage whose magnitude is a function of the distance required to stop the car from the speed at which it is traveling. The magnitude of the sum of these two voltages is compared with the magnitudes of discrete voltages proportional to the locations of the landings to scan the landings to determine that at which the next stop will be made. Upon the receipt of a signal that a stop is required at a landing being scanned that landing is selected and a signal suitable to control the deceleration of the car as a function of its distance from the selected landing is produced in response to the difference between a signal signifying the location of the selected landing and a signal signifying the location of the car. When the car approaches within a predetermined distance of the selected landing equipment which functions in the same way but which measures the distance between the car and the selected landing more accurately than the foregoing is used to control the final approach of the car to a stop.

United States Patent [72] Inventors Herbert Frederick Voigt Flushing;Otto Albert Krauer, Tuckahoe; Harvey Ronald Schor, Rockaway Park, N.Y.[21] Appl. No. 795,841 [22] Filed Feb. 3, 1969 [45] Patented Mar. 16,1971 [73] Assignee Otis Elevator Company New York, N.Y.

[54] LANDING SELECTOR APPARATUS 14 Claims, 3 Drawing Figs.

[52] US. Cl 187/29, 318/18 [51] Int. Cl B66b 1/52 [50] Field of Search187/29; 3 l 8/20.25O

[56] References Cited UNITED STATES PATENTS 3,146,857 9/1964 Bosshard187/29 3,422,928 H1969 Bruns 187/29 Primary Examiner-Cris L. RaderAssistant Examiner-WE Duncanson, .lr. Attorneys-Joseph L. Sharon andRobert T. Mayer ABSTRACT: Landing selector apparatus for use in anelevator control system. An output voltage whose magnitude signi-; fiesthe location of the car in the hoistway is added to a voltage whosemagnitude is a function of the distance required to stop the cartrom thespeed at which it is traveling. The magnitude of the sum of these twovoltages is compared with the magnitudes of discrete voltagesproportional to the locations of the landings to scan the landings todetermine that at which the next stop will be made. Upon the receipt ofa signal that a stop is required at a landing being scanned that landingis selected and a signal suitable to control the deceleration of the caras a function of its distance from the selected landing-is produced inresponse to the difference between a signal signifying the location ofthe selected landing and a signal signifying the location of the car.When the car approaches within a predetermined distance of the selectedlanding equipment which functions in the same way but which measures thedistance between the car and the selected landing more accurately thanthe foregoing is used to control the final approach of the car to astop.

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INVENTORS HERBERT'FREDRICK VOIGT OTTO ALBERT KRAUER HARVEY RONALD SCHORBY ffl/ yv- ATTORNEY LANDHNG SELEICTQR AhFARA'llUS This is an inventionin the elevator art. Specifically it involves landing selector apparatusfor use in an elevator control system.

That part of an elevator control system which is commonly referred to asits landing selector apparatus performs two primary functions. it scansthe landings in advance of the approach of the car to select the one atwhich the next stop will be made and after selecting a landing itprovides control signals to the elevator motor control system to enableit to decelerate the car in accordance with its distance from theselected landing so as to insure that the car stops accurately at thelanding.

Many types of landing selectors have been designed and constructed inthe past which are capable of adequately performing these functions.Most of them however are heavy, cumbersome essentially complicatedmechanical devices. Recently, it has become most desirable to makeselectors which not only are both lighter and more compact but also areless complicated mechanically. The problem is that where this has beenattempted the apparatus which has resulted either is more expensive tobuild and install than comparable previous selectors or is notcomparable to previous selectors in that it is incapable of performingadequately, especially in high rise in- It is another object of thisinvention to provide a light, compact, mechanically simple landingselector which is comparable functionally to previous selectors andwhich can be built and installed at a price which is competitive withthat of previous selectors.

in carrying out the invention a first car position potentiometerfunctioning as a first car position signal means has its wiper connectedto the car to produce a first car position voltage the magnitude ofwhich signifies the location of the car in the hoistway. A summationcircuit adds the magnitude of this voltage to the magnitude of a voltagewhich is function of the speed of the car. By suitable scaling thisproduces a voltage which signifies a location in advance of the locationof the car at a distance which is substantially no greater than thedistance required to stop the car from the speed at which it istraveling. A comparison means in the form of individual landingcomparators compares the magnitude of this advance location voltage withthe magnitudes of output voltages produced by a landing position voltagegenerating means in the form of an individual potentiometer for eachlanding, each of which produces a discrete voltage the magnitude ofwhich distinguishes its associated landing from every other landing inthe hoistway. Upon a predetermined relationship existing between themagnitude of the advance location voltage and the magnitude of anydiscrete landing voltage an output signal is produced indicating thatthe car is located substmtially at stopping distance from the landingassociated with that discrete voltage. if a signal which indicates thata stop is required at that landing coexists with the stopping distancesignal for that landing a landing selection relay associated with thatlanding is energized to indicate its selection as the landing at whichthe next stop will be made. in this way, each of the landings is scannedfor selection in advance of the approach of the car. Upon selection, thewiper of the first car position potentiometer is disconnected from thesummation circuit and its resistance element is connected in a bridgecircuit comprising a comparison means which compares the output voltageof the wiper t" the first car position potentiometer with the outputvoltage produced by a reference signal generating means in the form of apotentiometer individual to the selected landing. This potentiometer hasits wiper permanently fixed mechanically and grounded electrically at aresistance which balances that at which the wiper of the first carposition potentiometer rests when the car is stopped at the selectedlanding. bridge circuit produces a voltage signifying the differencebetween the location of the car and the location of the selected landingwhich after the generation of a signal to stop at the selected landingis suitable to control the deceleration of the car in its approachthereto. Upon the approach of the car to within a predetermined distanceof the selected landing a switching means switches the control of thedeceleration of the car from the foregoing to other equipment which moreaccurately indicates the distance of the car from the selected landing.This latter equipment includes second car position signal means in theform of the two otentiometers, one or the other of which produces asecond car position voltage which is operable to signify the location ofthe car at any position within the predetermined distance of each of thelandings. Additional comparison means in the form of a bridge circuitcompares the magnitude of the second car position voltage from aselected one of the two second car position potentiometers with avoltage individual to the selected landing produced by another referencesignal generating means. This means also includes an individualpotentiometer for each landing. The potentiometer for a particularlanding has its wiper permanently fixed mechanically and groundedelectrically at a resistance which balances that at which the wiper ofthe selected potentiometer reset when the car is located at thatparticular landing. As a result of this comparison, a voltage isproduced which is indicative of the distance of the car from theselected landing and which is suitable to decelerate the car to a stopin its final approach to the floor.

Other objects, features and advantages of the invention may beascertained from the foregoing and from the following description andappended claims when considered in conjunction with the accompanyingdrawing, in which:

FIG. 1 is a simplified schematic of an elevator control system includingthe herein disclosed landing selector apparatus;

HQ. 2 is a circuit diagram of switching logic circuits used in theherein disclosed landing selector to operate individual landingselection relays;

H6. 3 is a circuit diagram of various switching logic circuits and acomparator circuit.

To simplify the disclosure, only those portions of an elevator systemnecessary for an understanding of the invention have been shown indetail, it being understood that many changes may be made in adaptingthis invention to commercial installations. Also, as illustrated, theelevator car serves but three landings, however, the invention issuitable for use in any commercial installation having any number oflandings.

Numerals in parentheses appended to some of the reference characters forinterconnecting lines in the drawing identify those FlGS. on which thecontinuation of these lines are located.

Prefix numerals l. and 2 and the prefix T in some of the referencecharacters signify the association of the equipment identified by thosecharacters with the first, second and top landings, respectively.

Referring to HG. l of the drawing, an elevator car ill and itscounterweight it in typical fashion are supported by hoist ropes llZ.The car moves whenever bralte i3 is lifted and motor it; receives powerfrom motor and operations control equipment 25 to rotate sheave in. inrotating sheave l6, shaft R8 of motor l4 also drives tachometergenerator 117 to provide a voltage on line VTACH proportional to thespeed of car l0.

Motor and operations control equipment 15 may be any suitable equipment,either the equipment disclosed in the copending ELEVATOR CONTROL SYSTEM"application of @tto Albert lirauer et al., Ser. No. 495,585 filed Oct.l3, i965 now Fat. No. 3,442,352 and assigned to the assignee of theinstant application or that disclosed in the copending SP -ElliDlQTATlON APPARATUS FOR ELEVATOR MOTGR CUNTRQL SYSTEM" application ofSidney Howard Benjamin et al., er. No. 795,842 filed concurrentlyherewith and assigned to the assignee of the instant application. beingpresently preferred.

Connected between car and counterweight ll is a tape 19 which is drivenover a sprocket 21 as car 10 moves between any of the landings Lll toLT. Sprocket 2ll drives the input shaft of gear box GBl. The output ofthis component drives both the input shaft of the gear box G82 andsliding contact, or wiper, BRli of multiturn first car positionpotentiometer Pl. Depending upon the conditions of contacts Kl-lll ofthe landing hold relay Ki l and contacts 1K1, 2K] and Tlil of the floorselection relays 1K, 2K and TK, the resistance element of potentiometerPi is connected either directly across the potential between line E2+and ground or in a bridge circuit with the resistance element of one offirst reference potentiometers llREi, ZREE or TREl across the potentialbetween lines E2+ and 152-. Sliding contact BRl is connected eitherthrough contacts KH3 of landing hold relay KH and resistor R1 to one ofthe input circuits of summation amplifier ADSUM or through contacts KHZof landing hold relay KH to the input circuit of high speed functiongenerator l-lSFG.

The output circuit from function generator HSFG is connected along lineHSF through contacts LSEl to motor and operations control equipment 15.An additional input circuit to motor and operations control equipment115 is along line l-lX from advance distance comparator HXCOM. Of thethree input circuits to this comparator, one is through contacts XD3 ofauxiliary down direction relay XD (coil not shown) to the potential ofline Ed: the second isthrough contacts XU3 of auxiliary up directionrelay XU (coil not shown) to the potential of line 54+ and the third isthrough resistor R7 to a speed responsive signal means includingcapacitive advance circuit AC and variable voltage clamping network VCL.Advance circuit AC is connected through contacts XUl of auxiliary updirection relay XU and resistor R6 to a negative voltage source providedby the potential of line Eland through contacts XDl of auxiliary downdirection relay XD and resistor R5 to a positive voltage source providedby the potential of line El+. Depending upon the established directionof travel one or the other of these connections provides a chargingcircuit for condenser GA. Contacts KHd of the landing hold relay KH andresistor R4 provide a resetting circuit for condenser OA. The outputcircuit from this condenser is connected through resistor R3 both to thepreviously mentioned input circuit to comparator HXCOM through resistorR7 and to the second input circuit of summation amplifier ADSUM throughresistor R2. Connected at the junction between resistors R2 and R3 isthe output circuit from variable voltage clamping'network VCL. Thisnetwork includes voltage follower amplifier VF, diodes Di and D2 andpositive and negative potential voltage sources illustrated as batteriesVS+ and VS. The input circuit to network VCL is connected from resistorR8 along line VTAC to tachometer generator 17.

The output circuit from summation amplifier ADSUM is connected toindividual landing comparators lCOM, 2COM and TCOM. An additional inputcircuit to each of these comparators is connected from the wiper of itscorresponding landing position potentiometer 1RE3, 2RE3 or TRE3. Theresistance element of each of these potentiometers is connected across apotential applied between line E5+ and ground. Each of the landingcomparators includes a built in time delay and changes the landingscanning output signal along line llC, 2C or TC, respectively, apredetermined time after the signals applied to its two input circuitsattain a predetermined relationship with respect to each other.

The output shaft of gear box CB2 is connected to sliding contacts, orwipers, BRA and BRB of rotary single turn second car positionpotentiometers PA and PB, respectively. The end terminals of thesepotentiometers are connected to lines E3+ and E3 so that theirresistance elements are connected in a bridge circuit with theresistance elements of second reference potentiometers TREE, ZREZ andTREZ whose end terminals are also connected to lines E3+ and E3.Contacts 1K2, 2K2 and TlKZ of landing selection switches 1K, 2K and TKconnect predetermined points on the resistance elements ofpotentiometers TREZ, ZREZ and TRE2 to ground potential through theirindividual wipers. Wipers BRA AND BRB are respectively connected throughcontacts KABl and KABZ to the input circuit of low speed functiongenerator LSFG. The output circuit from this generator is connectedthrough contacts LSE2 along line LSF to another input circuit of motorand operations control equipment 15.

The coil of each of the landing selection relays 1K, 2K and TK shown inFlG. 2 is connected through an associated relay driver circuit RDlK,RDZK and RDTK to an individual switching logic circuit. Each of thesecircuits is implemented by six NAND units illustrated as AND units AN!to ANo with inverted outputs as conventionally symbolized by the smallcircles in their output circuit lines.

The switching logic circuits of FIG. 3 are similarly implemented by NANDunits illustrated as AND units with inverted outputs. Each of theindividual landing units lAND9, 2AND9 and TAND9 in the coil circuit ofsecond car position potentiometer selection relay KAB has an associatedmanual single pole double throw switch lAB, ZAB and TAB in one of itsinput circuit lines. For reasons which will be more apparent later, eachof the movable contacts of these switches is permanently connected toeither of its associated fixed contacts A or 8. Contact A is selectedfor a particular landing if when car it) is stopped at that landingwiper BRA (H6. 1) is closer to the midpoint of the resistance element ofits potentiometer than wiper BRB is to its, and vice versa.

One of the input circuits of low speed enable comparator LSECOM of HO. 3is connected to high speed function generator HSFG (FIG. 1) along linel-lSF. Of the other two inputs circuits, one is connected to thepotential of line E6+ through contacts XDZ of auxiliary down directionrelay XD and the other to the potential of line E6 through contacts XUZof auxiliary up direction relay XU. Low speed enable comparator LSECOMproduces an output signal to energize the coil of low speed enableswitch LSE through relay driver RDLQE whenever the magnitude of thesignal along line HSF is less than the magnitude of the potential ofeither line E6+ or E6- provided in the first case that the up directionof travel is established and in the second that the down direction oftravel is established.

Before proceeding to a detailed description of operation it willfacilitate matters to understand that first car position potentiometerPl is a multitum rotary potentiometer and that the ratio of gear box G81is so selected that wiper BRl makes no more than one full transit fromone end terminal of the resistance element ofpotentiometer P1 to theother in response to the total travel of the car from one end of thehoistway to the other in one direction of travel. in other words, thelocation of car 10 at each particular position in the hoistway isdistinguished from its location at every other position by theresistance value of potentiometer P1 at which wiper BRl is located.Accordingly, when the resistance element of potentiometer Pl isconnected between the potential of line E2+ and ground, the location ofthe car at each landing is distinguished from its location at everyother landing by a different and discrete voltage magnitude appearing atwiper BRl.

Contacts lKl, 2K1 and TKl (FIG. 1) of landing selection relays 1K, 2Kand TK connect the wipers of their associated first referencepotentiometers lREll, 2REll and TREE to ground. The wiper of each ofthese potentiometers is mechanically fixed in a permanent position at aresistance value which bears the same relationship to the totalresistance of its associated resistance element as the height of itscorresponding landing bears to the total vertical rise of the hoistway.The resistance value at the wiper of each first reference potentiometeris proportional to that resistance value of potentiometer H whichdistinguishes the individual landing with which each referencepotentiometer is associated. The proportionality factor is determined bythe relationship between the total resistance of the resistance elementsof the first reference potentiometers and the total resistance of theresistance element of potentiometer Pl. in this way, whenever car 10 isstopped at a landing the bridge circuit formed by these components isbalanced. Similarly, the wipers of landing position potentiometers ERES,ZREB and TREE v are-also mechanically fixed in permanent positions atresistance values proportional to those of potentiometer Pi whichdistinguish their respective landings.

in the presently described tested embodiment second car positionpotentiometers PA and PB are single turn rotary potentiometers whosewipers, ERA and BRB can turn continuously through zero in eitherdirection. The ratios of gear boxes G81 and G82 are such that the wiperof each potentiometer makes one complete revolution for each eight feetof car travel in the hoistway. During each revolution each wiper, BRAand BRB, travels progressively from the end terminal corresponding tothe zero ohms position on the resistance element of its respectivepotentiometer to the end terminal corresponding to its maximumresistance value into a deadband region, or unusable portion. Thepotentiometers are arranged however so that the wipers start theirtravel through the unusable portions of their respective potentiometers180 apart. Thus any time either one is traveling through its unusableportion the other is traveling through its usable portion. Thatpotentiometer is selected for use at a particular landing whose wiper isclosest to the midpoint of its resistance element, or to put it anotherway, is farthest from its unusable portion, when the car is stopped atthat landing. This insures a sufficient portion of the resistanceelement of the selected potentiometer on each side of the associatedwiper at every landing at which the car stops. The wiper of the secondreference potentiometer l-REZ, ZREZ or TREZ associated. with aparticular landing is mechanically fixed in a permanent position at aresistance value proportional to that at which the wiper of the secondcar position potentiometer selected for use at that particular landingis located when the car is stopped thereat so as to balance the bridgecircuit formed by those components in that situation. Stated otherwise,the wiper of a particular second potentiometer is stationarily locatedat a resistance value which forms the same ratio with the totalresistance of the particular potentiometer as the resistance value atthe wiper of the second car position potentiometer selected for use withthe particular second reference potentiometer forms with the totalresistance of the selected second car position potentiometer when thecar is located at the landing associated with the particular secondreference potentiometer.

With the foregoing in mind assume car til is stopped at landing Li whenit is prepared for future travel in the up direction and receives asignal to start in any suitable manner. For example, in the elevatorsystem of US. Pat. No. 3,149,305, issued Sept. 15, 1964 to William FrankGlaser et al., the car is prepared for future travel in the up directionby the operation of auxiliary up direction relay XU in response to theregistration of a car or hall call at a landing above the location ofthe car. A signal to start is generated in that system by the closing ofcontacts S2 of starting switch S in response to the operation of eitherauxiliary up direction relay XU or auxiliary down direction relay XDtogether with the release of loading time relay NT. Assume the operationin the present system is similar and that the closing of contacts S2(not shown) causes motor and operations control equipment E5 to generatea binary i signal along line SS. This causes And circuit Ais lDd and itsassociated inverter (FIG. 3) to change their output signal to the binary1 condition. in response landing hold relay KH releases closing contactsKl-ii, KH? and Kiid. The closing of these first two contact pairsapplies a positive potential with respect to ground, the magnitude ofwhich signifies the location of car it), through wiper Bitll, contactsKi-i3 and resistor Ril to one input circuit of summation arnpiifierADSUit i. v

addition, assume the preparation of car it) for future up travei, as inthe forementioneol Glaser et al. patent, operates auxiliary up directionrelay XU. This closes contacts Xi-Jil (HG. i) and opens contacts XUZ(FIG. 3) and XUT (FiG. ii). The closing of contacts XUil starts tocharge condenser QA through resistor R6 and previously closed contactsKHS with the negative potential of line Ei-. This enables it toapply anincreasing negative voltage through resistor R2 and R3 to the otherinput circuit of summation amplifier ADSUM. The

potential of this applied voltage is limited to a predeterminedmagnitude because diode D1, voltage source VS- and voltage followeramplifier VF of variable voltage clamping network VCL acts as a sink toany potential above that magnitude. The initial level of the sink ishigh enough, however, to permit the magnitude of the voltage fromcondenser CA to exceed the magnitude of the potential along line E4-applied to advance distance comparator HXCOM through contacts X03. Whenthis occurs comparator l-lXCOM applies a signal along line HX to motorand operations control equipment to cause it to lift brake 13 and toprovide a speed control voltage to motor M to rotate sheave 16. As thecar starts to move tachometer generator l7 applies a voltageproportional to the car speed along line V and through resistor R8 tonetwork VCL which raises the absolute magnitude of the sink formed bythe diode Di, source VS and amplifier VF in accordance with the speed ofthe car.

in the described tested embodiment advance circuit AC and clampingnetwork VCL have been so constructed that an in creasing negativepotential voltage the maximum magnitude of which is equivalent to 15feet in the hoistway is applied to amplifier ADSUM before the cartravels any appreciable distance or reaches any appreciable speed. lnother words, the initial level of the sink provided by network VCL ishigh enough to permit condenser 0A to charge to a potential themagnitude of which is equivalent to 15 feet in the hoistway without anyvoltage being applied along line V This is satisfactory to providesufficiently early indications of advance car locations to enablesuitable hall lantern operation on any length of trip.

Except for the 15 foot offset the voltage along line V from tachometergenerator 17 otherwise causes network VCL to control the negativepotential output voltage from condenser QA so that it is substantiallyproportional to the actual speed of car id. By suitable scaling themagnitude of this voltage is made substantially proportional to thedistance required to stop the car in a predetermined manner from thespeed at which it is traveling. As a result of the algebraic summationit performs, amplifier ADSUM produces a variable output volt age themagnitude of which satisfactorily signifies locations in advance of thelocation of the car which in accordance with car speed is notsubstantially greater than stopping distance ahead. This voltage iscompared through landing comparators iCOM, ZCOM and TCQM to the outputvoltages from the wipers of landing position potentiometers EREB, ZREB,and TREEi and in this way each of the landings is scanned when the caris located at position which is substantially no farther away in thedirection of travel than stopping distance for the speed at which thecar is traveling.

initially the increasing magnitude of the negative potential voltagefrom condenser QA causes the magnitude of the output voltage fromamplifier ADSUM to decrease to within a predetermined amount of themagnitude of the voltage applied to second landing comparator ZGOM fromthe wiper of the landing position potentiometer for the second landingZREB. As a result after the inherent time delay of comparator 200M alanding scanning signal in the form of a binary 1 signal signifying theadvance location of the car at the second landing appears along line 2C.if at this time a stop were required at the second landing the binarysignal along line 2C would cooperate with a signal signifying therequirement of the stop to cause motor and operations control equipmentR5 to produce a signal signifying that the second Eanding is to beseiected as the one at which the next stop will be made. Assume howeverthat no such, requirement exists and that the car continues to travel upthe hoistway. This causes its speed to increase until it reaches fullrated running speed at which time the output signal from tachometergenerator It? along line V enables advance circuit AC to produce anoutput voltage equivalent to the full speed stopping distance. Theselector is now scanning landings at full speed stopping distance inadvance of the location of the car.

Assume the car reaches a location such that the magnitude of thescanning output voltage from amplifier ADSUM decreases to within apredetermined magnitude of the voltage applied to top landing comparatorTCOM from the wiper of landing position potentiometer TRE3. Thisproduces a binary 1 signal along line TC after the expiration of thetime delay of comparator TCOM. Assume also that a signal signifying thata stop is required at the top landing has been generated in motor andoperations control equipment 115. Such a signal would be generated asthe result of the existence of a top landing hall or a car call. Thecoincidence of the existence of such a call and the existence of thelanding scanning signal in the form of a bi nary 1 signal along line TCsignifies that the top landing is to be selected as the one at which thenext stop will be made. As a result, motor and operations controlequipment 15 operates starting switch S to its released conditionsimilar to the manner in which it is so operated in the forementionedGlaser et a1. patent, opening contacts S2 (not shown) and causing thesignal along line SS (FIG. 3) to change to the binary value. The outputsignal from And circuit ANDA and its inverter thereupon changes to thebinary I value causing the energization of the coil of landing holdrelay KH through relay driver RDKH. This opens contacts KHI, KH3 andKI-lb and closes contacts KHZ.

The opening of contacts KHll and KI-I3 (FIG. I) interrupts theapplication of the output'of wiper BRl of potentiometer P1 to summationamplifier ADSUM. Notwithstanding the consequent interruption of one ofthe inputs to comparator TCOM, the binary 1 signal along line TC ismaintained until the expiration of the time delay of the comparator. Theopening of contacts xns (FIG. 3) causes the application of a binary llsignal along line Ki-IL (FIG. 3). At the same time binary l signals areapplied along lines SE and TC to top landing and circuit TANI (FIG. 2).As a result a binary l signal is applied along line TAP to top landingAND circuit TAN4. This signal together with binary ll signal applied tocircuit TANd along line KI-IL causes it and its inverter to produce abinary 0 signal. As a result the signal along line TKAP changes to thebinary 1 value and top landing selection switch TM is energized throughAnd circuit TAhlo and relay driver RDTK to select the top landing as theone at which the next stop will be made. The operation of relay TKcloses contacts TKl to connect the resistance element of potentiometerP1 in a bridge circuit across the potential between lines E2+ and E2-with the resistance element of top landing first reference potentiometerTREl.

Ground potential at the wiper of potentiometer TREl signifies thelocation of the top landing while the voltage at wiper BRl ofpotentiometer P1 in relation to this signifies the location of the car.As a result, the output voltage from wiper BRl is proportional to thedistance between the location of car 10 and that of the top landing.This is applied through contacts KHZ to high speed function generatorI-ISFG to produce a signal which is applied to motor and operationscontrol equipment 15 through contacts LSEl. In response, upon thegeneration of a signal to stop, equipment 15 decelerates the car as afunction of its distance from the top landing.

The output from high speed function generator I-ISFG is also appliedalong line I-ISF to low speed enable comparator LSECOM. When this signaldecreases below the magnitude of the potential applied along line 56+ tosignify the location of car 10 within a predetermined distance of thetop landing, low speed enable relay LSE operates through contacts Iii-i7and relay driver RDLSE. This opens contacts LSEl and closes contactsLSE2 to disconnect the high speed function generator from motor andoperations control equipment l and connect low speed function generatorLSFG thereto.

In the meantime the binary 1 signal along line TKAP and that from lineVl-lthrough resistor TREE causes top landing and circuit TAND9 wd itsinverter to produce a binary it signal. This energizes relay KAB throughrelay driver KDKAB. Thus contacts KABI are closed connecting theresistance element of second car position potentiometer PA in a bridgecircuit across the potential between lines E3+ and E3- with theresistance element of top landing second reference potentiometer TREZ.

In the described tested embodiment, the bridge circuit formed by secondcar position potentiometer PA and PB and the second referencepotentiometers lREZ, ZREZ and TREZ becomes operative withinapproximately two feet on either side of a selected landing at which astop is being made. Within this predetermined distance the groundpotential at the wiper of the second reference potentiometer associatedwith the selected landing signifies the location of the landing whilethe voltage and the wiper of the selected second car positionpotentiometer in relation to ground potential signifies the location ofthe car. Accordingly, with the top landing selected the bridge circuitformed by potentiometer PA and second reference potentiometers TREZprovides an output voltage from wiper BRA which is a function of thedistance between the car and the top landing at any car location withinapproximately two feet of that landing. This applied through contactsKABI to low speed function generator LSFG which provides a signalthrough contacts LSE2 along line LSF to motor and operations controlequipment 15 to control the final approach of the car to a satisfactorystop within suitable accuracy of the top landing.

From the foregoing it is apparent that the present invention provideslanding selector apparatus for use in an elevator control system whichnot only scans landings in advance of the approach of the car to selectthe one at which the next stop will be made but also provides controlsignals to the elevator motor control system to enable it to deceleratethe car in accordance with its distance from the selected landing so asto insure that the car stops accurately at that landing.

Moreover, the apparatus is mechanically simple. Upon being adjusted tosuit the peculiarities in landing heights of any installation theapparatus operates with the wipers of all but three of itspotentiometers located in stationary positions. Thus in operation themechanical parts that are movable include, in addition to suitablebearings, only a drive sprocket rotated by a tape connected between thecar and its counterweight, two geared speed reduction units and threepotentiometers.

It is to be noted also that secondary functions that it is desirable tohave a selector perform are also capable of being performed by theapparatus of this invention. For example, satisfactory advance halllantern and car position indications are available if the output signalsalong lines 1C, 2C and TC from landing comparators ICOM and TCOM areemployed in conjunction with landing selection switches IK, 2K and TK tocontrol these functions. Discrete distance signals indicative of thedistance between the car and a selected landing are available throughthe use of comparators similar to low speed enable comparator LSECOM.Signals indicative of scanned positions in advance of the location ofthe car are also available. These can readily be generated through theuse of comparators similar to advance distance comparator HXCOM. Theoutput signals along line ADL and m of FIG. 3 are other signalsdesirably generated by a selector machine. The former indicates that alanding has been selected and that the logic circuits have operated tomaintain such an indication. The latter is in inverse of the former.

Other functions which the disclosed apparatus is capable of performingwill be apparent to those skilled in the elevator art. Variousmodifications of this apparatus are also possible, and it is intendedthat the foregoing be considered illustrative and not exclusive or inany sense limiting.

We claim:

1. Landing selector apparatus for use in an elevator system forproviding control over the movement of an elevator car in response tosignals to start and to stop at selected ones of a plurality of landingsin its hoistway, said apparatus including,

first reference signal generating means responsive to the selection of aparticular one of said landings generating a first reference signalsignifying the location of said landing, first car position signal meansresponsive to the selection of said particular landing and to themovement of said car producing a 5 first car position signal, firstcomparison means responsive to the selection of said particular landingreceiving and comparing said first reference signal and said first carposition signal and in response thereto generating a first output signalsignifying the distance between the location of said car and thelocation of said selected landing and suitable after the generation of asignal to stop thereat to control a portion of the deceleration of saidcar in its approach thereto; second reference signal generating meansresponsive to the deceleration of said car to within a predetermineddistance of said selected landing generating a second reference signalsignifying the location of said selected landing; second car positionsignal means responsive to the approach of said car to Within saidpredetermined distance of said selected landing and to the movement ofsaid car generating a second car position signal; second comparisonmeans responsive to the approach of said car to within saidpredetermined distance of said selected landing receiving and comparingsaid second reference signal and said second car position signal and inresponse thereto generating a second output signal signifying thedistance between the location of said car and the location of saidselected landing and suitable within said predetermined distance thereofto control the final approach of said car to a stop thereat; andswitching a means responsive to approach of said ear to within saidpredetermined distances of said selected landing switching the controlof the approach of said car from said first output signal to said secondoutput signal.

2. Landing selector apparatus according to claim ll, wherein 5 saidsecond car position signal means includes a first potentiometer having awiper which is connected to the elevator car and is rotated by themovement of said car through the full range of the usable resistanceportion of its potentiometer progressively from its zero ohms positionto its maximum resistance value and through its usable portion to itszero ohms position again for each predetermined portion less than thetotal possible vertical movement of the car in said hoistway.

3. Landing selector apparatus according to claim 2, wherein said secondcar position signal means includes a second potentiometer having a wiperwhich also is connected to the elevator car and is rotated by themovement of said car through the full range of the usable resistanceportion of its potentiometer progressively from its zero ohms positionto its maximum resistance value and through its unusable portion to itszero ohms position again for each predetermined portion less than thetotal possible vertical movement of the car in said hoistway, said firstand said second potentiometers being so selected and their wipers beingso connected to said car that throughout the total possible verticalmovement of said car whenever the wiper of one potentiometer is passingthrough the unusable portion of its potentiometer the wiper of the otherpotentiometer is passing through the usable portion of itspotentiometer. 60

4. Landing selector apparatus according to claim 3, wherein said secondreference signal generating means includes a plurality of resistanceelements, a different one for each of said landings and each having anoutput connection, the output connection on a particular resistanceelement being located at a resistance value which forms the same ratiowith the total resistance of said particular element as the resistancevalue at the wiper of one of said potentiometers forms with the, totalresistance of said potentiometer when the car is located at the landingassociated with said particular resistance element.

5. Landing selector apparatus according to claim 3, wherein said firstcar position signal means is operable prior to the selection of alanding to produce a voltage which distinguishes each location of thecar from every other location by a different discrete magnitude. 5

LII

ill)

6. Landing selector apparatus according to claim 5, including speedresponsive signal means operating in response both to a signal to startand to the actual speed of said car and producing a speed responsivevoltage the magnitude of which signifies at least the minimum distancerequired to stop said car in a prescribed manner from the speed at whichit is moving; summation means operable prior to the selection of alanding receiving and algebraically summing the voltage produced by saidfirst car position signal means and said speed responsive voltage andproducing a variable advance location voltage the magnitude of which inrelation to a particular reference signifies locations in advance of thelocation of said car; landing position voltage generating meansgenerating for each landing to a landing position voltage the magnitudeof each of which in relation to said particular reference distinguishesits associated landing from any other in said hoistway; landingcomparator means receiving and comparing said variable advance locationvoltage and said landing position voltages and producing an individuallanding scanning signal whenever a predetermined relationship existsbetween said varying advance location voltage and the landing positionvoltage corresponding to any landing; and landing selection switchingmeans operating in response to the simultaneous existence of both asignal signifying a requirement to stop at a particular landing and thelanding scanning signal for that particular landing 7. Landing selectorapparatus according to claim 6, wherein said speed responsive signalmeans includes a capacitive circuit and a negative and a positivevoltage source connected thereto, said capacitive circuit operating inresponse to a signal to start and producing said speed responsivevoltage by being charged from either said negative or said positivevoltage source, depending upon the direction of car movement which isestablished.

8. Landing selector apparatus according to claim 7, wherein said speedresponsive signal means includes both a variable voltage clamp connectedto said capacitive circuit which limits the magnitude of said speedresponsive voltage which can be received by said summation means and atachometer generator responsive to the movement of said car producing anoutput voltage signifying the actual speed of said car which is appliedto said variable voltage clamp and varies the limit of the magnitude ofthe speed responsive voltage which can be received by said summationmeans.

9. Landing selector apparatus according to claim 8, wherein said firstreference signal generating means includes an individual first referencepotentiometer for each landing, the resistance element of each of whichis connected across a predetermined potential between two supply linesand the wiper of each of which in response to the selection of itsassociated landing is connected to ground at a resistance value whichbears the same relationship to the total resistance of its associatedresistance element as the height of its corresponding landing to thetotal vertical rise of the hoistway,

ll}. Landing selector apparatus according to claim 9, wherein said firstcar position signal means includes a potentiometer whose wiper isconnected to said car and is rotated thereby no more than from oneterminal of the resistance element of said potentiometer to the other asthe car moves through its total possible vertical movement in thehoistway, each of the two terminals of said potentiometer beingconnected to a different one of said supply lines, the one line itselfbeing connected to ground potential in response to a signal to start,said ground connection being removed and said car position potentiometerand a first reference potentiometer being connected to said firstcomparison means in response to the selection of the landing associatedwith said first reference potentiometer. said first comparison meanscomprising a bridge circuit of said car position potentiometer and saidindividual first reference potentiometer.

ill. in an elevator system for building hoistway having a plurality oflandings including a lower and an upper terminal landing, an elevatorcar serving said plurality of landings in response to signals to startfrom and to stop at selected ones of said landings, a hoisting motormoving said car up and down between said lower and upper terminallandings to serve said plurality of landings, a rotary car positionpotentiometer hav ing a wiper and a resistance element with two endterminals, said wiper being connected to said car and rotated by themovement thereof through its path of movement over the resistanceelement of said potentiometer in one of its rotary directions from oneend terminal to the other more than once for each movement of said carfrom one terminal landing to the other in one of its directions ofmovement, resistance means having two end terminals, an electricalconnection on said resistance means at a resistance value which bearsthe same relationship to one of its end terminals as the resistancevalue at said wiper bears to one of the end terminals of saidpotentiometer when the car is located at a particular one of saidlandings, and comparison means operable to compare the resistance valueat the electrical connection on said resistance means with theresistance value at the wiper of said potentiometer, said comparisonmeans being operable in response to a signal to stop at said particularlanding and to the approach of said car to within a predetermineddistance thereof to produce thereafter throughout the stopping operationof said car a distance controlled signal the magnitude of which is afunction of the distance between said car and said particular landing.

12. In an elevator system according to claim 11, including a secondrotary car position potentiometer having a wiper and. a resistanceelement with two end terminals, said wiper also being connected to saidcar and rotated by the movement thereof through its path of movementover the resistance element of its potentiometer in one of its rotarydirections from one end terminal to the other more than once for eachmovement of said car from one terminal landing to the other in one ofits directions of movement, and wherein said resistance means includes aplurality of reference potentiometers, each having a resistance elementwith two end terminals, and each particular reference potentiometerhaving a wiper providing an electrical connection at a resistance valueof its resistance element which bears the same relationship to one ofits end terminals as the resistance value at the wiper on a selected oneof said car position potentiometers bears to one of its end terminalswhen the car is located at a different one of said landings, wherebyeach reference potentiometer is individually associated with a differentone of said landings.

13. in an elevator system according to claim 12, wherein each of saidcar position rotary potentiometer is a single turn one and for eachmovement of the car between adjacent landings the wiper on eachpotentiometer is rotated through the full range of the usable resistanceportion of its potentiometer progressively from its end terminalcorresponding to its zero ohms position to its end terminalcorresponding to its maximum resistance value and through. its unusableportion to its zero ohms position again, said potentiometers being soselected and their wipers being so connected to said car that throughouta movement of the car from one terminal landing to the other wheneverone wiper is passing through the unusable portion of its potentiometerthe other wiper is passing through the usable portion of itspotentiometer.

14. in an elevator system according to claim 13, wherein said comparisonmeans includes a voltage source, circuit means connecting the endterminals of said car position potentiometers and said referencepotentiometers in a bridge circuit across said voltage source, landingselection means connecting the wiper on the reference potentiometerassociated with a particular landing to ground in response to theselection of said particular landing as the one at which the next stopwill be made, and car position potentiometer selection means operable,after said ground connection is made and when said car approaches towithin said predetermined distance of said selected landing, to selectthe wiper of one of said car position potentiometers as the output ofsaid bridge circuit from which said distance controlled signal isproduced.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 570,630 Dated March 16, 1971 Herbert Frederick Voigt, Otto Albert Krauer tfl and Harvev Ronald S'chor It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 9, line 30, "distances" should read distance Column 9, line 39,"usable" should read unusable Column 9, line 75, "discrete magnitude"should read disc.

potential magnitude Column 10, line 14, "landing to a landing" shouldread landing a landing Column 10, line 73, "for building" should readfor a building Under References Cited, UNITED STATES PATENTS, "3,422,9

l/l969, Bruns, 187/29' Should read 2,699, 226, l/l955, Br

Signed and sealed this 1 0th day of August 1971 (SEAL) Attest:

EDWARD M.FLETGHER,JR WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents

1. Landing selector apparatus for use in an elevator system forproviding control over the movement of an elevator car in response tosignals to start and to stop at selected ones of a plurality of landingsin its hoistway, said apparatus including, first reference signalgenerating means responsive to the selection of a particular one of saidlandings generating a first reference signal signifying the location ofsaid landing, first car position signal means responsive to theselection of said particular landing and to the movement of said carproducing a first car position signal, first comparison means responsiveto the selection of said particular landing receiving and comparing saidfirst reference signal and said first car position signal and inresponse thereto generating a first output signal signifying thedistance between the location of said car and the location of saidselected landing and suitable after the generation of a signal to stopthereat to control a portion of the deceleration of said car in itsapproach thereto; second reference signal generating means responsive tothe deceleration of said car to within a predetermined distance of saidselected landing generating a second reference signal signifying thelocation of said selected landing; second car position signal meansresponsive to the approach of said car to within said predetermineddistance of said selected landing and to the movement of said cargenerating a second car position signal; second comparison meansresponsive to the approach of said car to within said predetermineddistance of said selected landing receiving and comparing said secondreference signal and said second car position signal and in responsethereto generating a second output signal signifying the distancebetween the location of said car and the location of said selectedlanding and suitable within said predetermined distance thereof tocontrol the final approach of said car to a stop thereat; and switchingmeans responsive to approach of said car to within said predetermineddistances of said selected landing switching the control of the approachof said car from said first output signal to said second output signal.2. Landing selector apparatus according to claim 1, wherein said secondcar position signal means includes a first potentiometer having a wiperwhich is connected to the elevator car and is rotated by the movement ofsaid car through the full range of the usable resistance portion of itspotentiometer progressively from its zero ohms position to its maximumresistance value and through its usable portion to its zero ohmsposition again for each predetermined portion less than the totalpossible vertical movement of the car in said hoistway.
 3. Landingselector apparatus according to claim 2, wherein said second carposition signal means includes a second potentiometer having a wiperwhich also is connected to the elevator car and is rotated by themovement of said car through the full range of the usable resistanceportion of its potentiometer progressively from its zero ohms positionto its maximum resistance value and through its unusable portion to itszero ohms position again for each predetermined portion less than thetotal possible vertical movement of the car in said hoistway, said firstand said second potentiometers being so selected and their wipers beingso connected to said car that throughout the total possible verticalmovement of said car whenever the wiper of one potentiometer is passingthrough the unusable portion of its potentiometer the wiper of the otherpotentiometer is passing through the usable portion of itspotentiometer.
 4. Landing selector apparatus according to claim 3,wherein said second reference signal generating means includes aplurality of resistance elements, a different one for each of saidlandings and each having an output connection, the output connection ona particular resistance element being located at a resistance valuewhich forms the same ratio with the total resistance of said particularelement as the resistance value at the wiper of one of saidpotentiometers forms with the total resistance of said potentiometerwhen the car is located at the landing associated with said particularresistance element.
 5. Landing selector apparatus according to claim 4,wherein said first car position signal means is operable prior to theselection of a landing to produce a voltage which distinguishes eachlocation of the car from every other location by a different anddiscrete magnitude.
 6. Landing selector apparatus according to claim 5,including speed responsive signal means operating in response both to asignal to start and to the actual speed of said car and producing aspeed responsive voltage the magnitude of which signifies at least theminimum distance required to stop said car in a prescribed manner fromthe speed at which it is moving; summation means operable prior to theselection of a landing receiving and algebraically summing the voltageproduced by said first car position signal means and said speedresponsive voltage and producing a variable advance location voltage themagnitude of which in relation to a particular reference signifieslocations in advance of the location of said car; landing positionvoltage generating means generating for each landing to a landingposition voltage the magnitude of each of which in relation to saidparticular reference distinguishes its associated landing from any otherin said hoistway; landing comparator means receiving and comparing saidvariable advance location voltage and said landing position voltages andproducing an individual landing scanning signal whenever a predeterminedrelationship exists between said varying advance location voltage andthe landing position voltage corresponding to any landing; and landingselection switching means operating in response to the simultaneousexistence of both a signal signifying a requirement to stop at aparticular landing and the landing scanning signal for that particularlanding.
 7. Landing selector apparatus according to claim 6, whereinsaid speed responsive signal means includes a capacitive circuit and anegative and a positive voltage source connected thereto, saidcapacitive circuit operating in response to a signal to start andproducing said speed responsive voltage by being charged from eithersaid negative or said positive voltage source, depending upon thedirection of car movement which is established.
 8. Landing selectorapparatus according to claim 7, wherein said speed responsive signalmeans includes both a variable voltage clamp connected to saidcapacitive circuit which limits the magnitude of said speed responsivevoltage which can be received by said summation means and a tachometergenerator responsive to the movement of said car producing an outputvoltage signifying the actual speed of said car which is applied to saidvariable voltage clamp and varies the limit of the magnitude of thespeed responsive voltage which can be received by said summation means.9. Landing selector apparatus according to claim 8, wherein said firstreference signal generating means includes an individual first referencepotentiometer for each landing, the resistance element of each of whichis connected across a predetermined potential between two supply linesand the wiper of each of which in response to the selection of itsassociated landing is connected to ground at a resistance value whichbears the same relationship to the total resistance of its associatedresistance element as the height of its corresponding landing to thetotal vertical rise of the hoistway.
 10. Landing selector apparatusaccording to claim 9, wherein said first car position signal meansincludes a potentiometer whose wiper is connected to said car and isrotAted thereby no more than from one terminal of the resistance elementof said potentiometer to the other as the car moves through its totalpossible vertical movement in the hoistway, each of the two terminals ofsaid potentiometer being connected to a different one of said supplylines, the one line itself being connected to ground potential inresponse to a signal to start, said ground connection being removed andsaid car position potentiometer and a first reference potentiometerbeing connected to said first comparison means in response to theselection of the landing associated with said first referencepotentiometer, said first comparison means comprising a bridge circuitof said car position potentiometer and said individual first referencepotentiometer.
 11. In an elevator system for building hoistway having aplurality of landings including a lower and an upper terminal landing,an elevator car serving said plurality of landings in response tosignals to start from and to stop at selected ones of said landings, ahoisting motor moving said car up and down between said lower and upperterminal landings to serve said plurality of landings, a rotary carposition potentiometer having a wiper and a resistance element with twoend terminals, said wiper being connected to said car and rotated by themovement thereof through its path of movement over the resistanceelement of said potentiometer in one of its rotary directions from oneend terminal to the other more than once for each movement of said carfrom one terminal landing to the other in one of its directions ofmovement, resistance means having two end terminals, an electricalconnection on said resistance means at a resistance value which bearsthe same relationship to one of its end terminals as the resistancevalue at said wiper bears to one of the end terminals of saidpotentiometer when the car is located at a particular one of saidlandings, and comparison means operable to compare the resistance valueat the electrical connection on said resistance means with theresistance value at the wiper of said potentiometer, said comparisonmeans being operable in response to a signal to stop at said particularlanding and to the approach of said car to within a predetermineddistance thereof to produce thereafter throughout the stopping operationof said car a distance controlled signal the magnitude of which is afunction of the distance between said car and said particular landing.12. In an elevator system according to claim 11, including a secondrotary car position potentiometer having a wiper and a resistanceelement with two end terminals, said wiper also being connected to saidcar and rotated by the movement thereof through its path of movementover the resistance element of its potentiometer in one of its rotarydirections from one end terminal to the other more than once for eachmovement of said car from one terminal landing to the other in one ofits directions of movement, and wherein said resistance means includes aplurality of reference potentiometers, each having a resistance elementwith two end terminals, and each particular reference potentiometerhaving a wiper providing an electrical connection at a resistance valueof its resistance element which bears the same relationship to one ofits end terminals as the resistance value at the wiper on a selected oneof said car position potentiometers bears to one of its end terminalswhen the car is located at a different one of said landings, wherebyeach reference potentiometer is individually associated with a differentone of said landings.
 13. In an elevator system according to claim 12,wherein each of said car position rotary potentiometer is a single turnone and for each movement of the car between adjacent landings the wiperon each potentiometer is rotated through the full range of the usableresistance portion of its potentiometer progressively from its endterminal corresponding to its zero ohms position to its end terminalcorresponding To its maximum resistance value and through its unusableportion to its zero ohms position again, said potentiometers being soselected and their wipers being so connected to said car that throughouta movement of the car from one terminal landing to the other wheneverone wiper is passing through the unusable portion of its potentiometerthe other wiper is passing through the usable portion of itspotentiometer.
 14. In an elevator system according to claim 13, whereinsaid comparison means includes a voltage source, circuit meansconnecting the end terminals of said car position potentiometers andsaid reference potentiometers in a bridge circuit across said voltagesource, landing selection means connecting the wiper on the referencepotentiometer associated with a particular landing to ground in responseto the selection of said particular landing as the one at which the nextstop will be made, and car position potentiometer selection meansoperable, after said ground connection is made and when said carapproaches to within said predetermined distance of said selectedlanding, to select the wiper of one of said car position potentiometersas the output of said bridge circuit from which said distance controlledsignal is produced.